The present invention relates to a system for the opening and closing of a two-part front window for the cab of a vehicle, particularly an excavator, having an upper and a lower pane. The lower pane, via rollers between guide rails, is movable into a lifted opened position and into a lowered closing position. Both panes are jointly able to be swivelled into a lockable clear-view position arranged under the cab roof.
From the German Patent Document DE-OS 31 50 786, a cab for a vehicle is known which has a two-part front window which comprises panes that are arranged vertically offset with one another. For the opening of the front window, the bottom pane can be moved vertically behind the top pane and both panes can be swivelled in guides under the roof of a cab. Furthermore, on the basis of the German Patent Document DE-OS 27 12 823, a one-part window for a cab is known which can be moved under the roof by means of a guiding rod and with the aid of a pneumatic spring.
An object of the invention is to provide a front window for a vehicle which permits optimal viewing conditions and which has panes that can be adapted to the respective working conditions in a simple manner and which ensure by way of guiding devices a common swivelling under the roof which does not hinder the driver.
This and other objects are achieved by the present invention which provides a system for opening and closing a two-part front window for the cab of a vehicle having an upper pane and a lower pane, and lower and upper guide rails and rollers. The lower pane is movable via the rollers between the guide rails into a lifted opened position and into a lowered closing position. The top and bottom panes are jointly swivellable into a lockable clear-view position under the cab roof. The bottom pane extends flush with respect to the top pane in the closed position and is held in a supported manner on the lower and upper guide rails.
Some of the advantages achieved by means of the invention are that the first lower guide rails of the bottom pane have a construction which permits a shifting as well as a swivelling about lower guide rollers for taking up a shifted position and a flush closed position. According to the German Patent Document DE-OS 31 50 786, such a possibility does not exist because of the rigid offset arrangement of the bottom pane with respect to the top pane.
The swivelling capacity of the bottom pane is achieved by a sliding plate which extends transversely with respect to the running path of each guide rail and introduces the upper roller into the vertical running path. At the same time, the slide plate interacts with a catch of a locking device so that, in the flush position of the two panes, the bottom pane is arrested in this position.
For a joint swivelling of the bottom pane together with the top pane under the roof of the cab, the upper guide rails of the bottom pane are fixedly connected with the top pane so that a swivel unit is formed which includes the top pane, the bottom pane as well as the pertaining guide rails.
So that the driver is not disturbed by the swivelling of this unit under the roof or need not duck his head when this unit is swivelled, the running paths of the guide rails of the top pane have a correspondingly curved design. This curvature is more pronounced in the lower area of the pane than in the upper area. As a result, a swivel path is achieved which results in a curved running course with respect to the driver's head at a relatively large distance.
For the swivelling restricted guiding of the unit, at least one control rod is also provided which is pivotally connected to the upper frame of the body structure and is, in each case, connected with the upper guide rails of the bottom pane. For aiding the swivelling movement, at least one pneumatic spring is used which is supported on the lateral frame of the body structure and is disposed on the control rod. With a rising swivel angle of the unit, the line of force of the pneumatic spring extends such that the opening into the clear view position is supported by the force.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.